docs: def get_context(self, name, value, attrs):
          """
          Return the context to use with the widget's template, e.g.
          {'widget': {
              'attrs': {'id': "id_repeat", 'required': True},
              'is_hidden': False,
              'name': "repeat",
              'required': True,
              'subwidgets': [... the context of all the component subwigets...],
              'template_name': "joyous/widgets/recurrence_widget.html",
              'value': "Tuesdays",
              'value_s': "Tuesdays",
              'value_r': "DTSTART:20181201\nRRULE:FREQ=WEEKLY;WKST=SU;BYDAY=TU",
              }}}
          """
          context = super().get_context(name, value, attrs)
          context['widget']['value_s'] = str(value)
          context['widget']['value_r'] = repr(value)
          return context